Скачать или смотреть Calling a Stored Procedure with String Output Parameter in SQL Server 2022 using ODBC

Learn how to successfully call a stored procedure with a `string output` parameter in SQL Server 2022 using the ODBC API. Explore the correct parameter configurations to avoid common errors.
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Resolving String Output Parameter Issues in SQL Server 2022 Stored Procedures

When working with stored procedures in SQL Server, you might run into challenges when passing output parameters, especially when those parameters are strings. If you’re using the ODBC API for database communication, you may be faced with an error that leaves you scratching your head. One common scenario involves calling a stored procedure with a string output parameter that simply does not work, while numeric parameters work without a hitch.

The Problem

In our example, we have a stored procedure defined as follows:

[[See Video to Reveal this Text or Code Snippet]]

The intention here is straightforward: input a string parameter and output the same string using the @ outParam parameter. However, when attempting to call this procedure from your application using ODBC, you might encounter an error indicating an invalid output parameter, specifically:

[[See Video to Reveal this Text or Code Snippet]]

This error bubbles up when the ODBC driver cannot work with the specified output parameter type.

The Solution

To fix this, it's essential to understand how parameter types work in ODBC. Particularly, you need to specify the correct SQL type for your output parameter. In your application code snippet, the issue arises from using SQL_LONGVARCHAR for the output parameter instead of the appropriate type.

Updating the Parameter Binding

To resolve the issue, modify the binding for your output parameter. Instead of using SQL_LONGVARCHAR, opt for SQL_VARCHAR as shown below:

[[See Video to Reveal this Text or Code Snippet]]

Summary of Required Changes

Input Parameter: Can remain as is, you should bind it as follows:

[[See Video to Reveal this Text or Code Snippet]]

Output Parameter: Change from SQL_LONGVARCHAR to SQL_VARCHAR to avoid deprecated types:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

In conclusion, calling a stored procedure with string output parameters in SQL Server 2022 using ODBC requires careful attention to the parameter types specified when binding. Ensuring that you use SQL_VARCHAR for output parameters will help eliminate errors related to deprecated types. This change will allow your stored procedure to function correctly, giving you the expected string output.

Now you're ready to handle string output parameters without a hitch in your applications!